Microbiology - Respiratory Tract Infections Flashcards
1
Q
What are our defence mechanisms against respiratory tract infections? Large bacteria? Small bacteria?
A
Large bacteria: caught in the mucus layer. Cilia on the mucous membrane move bacteria to back of throat (are then swallowed).
Small bacteria: alveolar macrophages phagocytose + lyse them.
2
Q
What are the general virulence factors for bacterial respiratory tract infections? (3)
A
- Attachment to mucosa by attachment factors (so they are not swept away by cillia)
- Inactivation of cillia (bacteria can then multiply at site of infection)
- Reproduction w/in macrophages - macrophages provide a safe haven for replication
3
Q
What are the upper respiratory tract infections? (6)
A
SOOPLE
Sinusitis Otitis Media Oral Cavity Infections Pharyngitis Laryngitis Epiglotitis
4
Q
What are the lower respiratory tract infections? (8)
A
BALD PCTC
Bronchitis Anthrax Lung Abscess Diphtheria Pneumonia COPD Exacerbation Tuberculosis Cystic Fibrosis
5
Q
What is bacterial sinusitis?
A
It is the inflammation of sinuses due to bacterial infection?
6
Q
How do the sinuses become infected?
A
The sinuses are usually sterile due to mucus flow through the ostia to nasal cavity. What happens, the ostia become obstructed (due to viral infection or allergies) and this blocks the sinusitis allowing for mucus to accumulate and cause infection.
7
Q
What are the SX of bacterial sinusitis?
A
Thick, purulent nasal discharge, congestion, facial pain and headache. (Less common SX - toothache and halitosis)
8
Q
How is bacterial sinusitis caused? What are some bacteria that cause bacterial sinusitis? What characterizes the nosocomial infections?
A
It is caused by the overgrowth of organisms normally found in the nasopharynx.
S. pneumonia
H. influenza (non-encapsulated)
Moraxella catarrhalis (mostly children)
Nosocomial infections (are polymicrobial, multiple-drug resistrant strains)
9
Q
How do you treat bacterial sinusitis?
A
Amoxicillin
10
Q
What is the physiology and structure of moraxella catarrhalis? Where is it normally found?
A
Gram negative diplococcus (other is neisseria meningitidis).
Normally found in nasopharynx (more common in children)
11
Q
What diseases are caused by moraxella catarrhalis? (3)
A
Otitis media
Sinusitis
Pneumonia (immunocompromised/COPD patients)
12
Q
How do you treat moraxella catarrhalis?
A
Antibiotics - depends on site of infection and other possible bacteria present.
13
Q
What is otitis media and its pathophysiology?
A
It is inflammation of the middle ear.
It occurs by blockage of the eustachian tubes in which sterile fluid accumulates in the middle ear allowing for bacteria from the nasopharynx to grow.
NOTE: Most acute otitis media follows viral URTI.
14
Q
What are the SX of otitis media?
A
Otalgia (ear pain)
Ottorhea (discharge)
Diminished hearing
Fever
15
Q
What are some bacteria that cause of otitis media?
A
- Strep pneumonia
- Haemophilus influenza (nonencapsulated)
- Moraxella catarrhalis (mostly in children)
16
Q
What is the treatment for otitis media?
A
Amoxicillin
17
Q
What is the cause of oral cavity infections? Virus/bacteria? Other reasons?
A
Viral/Bacteria: Usually herpes simplex virus and candida albicans and astinomycosis (which causes actinomuces israelii) - the infections are polymicrobial. Infection due to slow growing anaerobe.
Other: Oral surgery, trauma and poor dental hygiene.
18
Q
What is usually seen in oral cavity infections?
A
Swelling of soft tissue along the angle of the jaw and neck or in the oral cavity. May develop draining sinus tract with yellow granules of pus (called sulfur granules).
NOTE: Actinomycosis abscesses grow larger as the disease progresses, often over months. In severe cases, they may penetrate the surrounding bone and muscle to the skin, where they break open and leak large amounts of pus, which often contains characteristic granules (sulfur granules) filled with progeny bacteria.
19
Q
What is the physiology and structure of actinomyces israelii? Gram stain? Structure? Anaerobic or aerobic or microaerophilic? Speed of growth?
A
GS: Gram positive rod
Structure: filamentous
Anaerobic/microaerophilic
Slow growing
20
Q
Where is Actinomyces israelii normally found? (3)
A
Normal flora of upper respiratory tract, GI tract and female genital tract.
21
Q
When does Actinomyces israelii cause infection?
A
Is it part of the normal flora, so it is in an opportunistic pathogen. It only causes disease when mucosal barrier is disrupted.
22
Q
What diseases do Actinomyces israelii cause? (4)
A
Oral - cervicofacial (oral cav. infect)
Thoracic disease
Abdominal disease
Pelvic disease - associated with IUD use
23
Q
How do you diagnose Actinomyces israelii?
A
Bacteria in the sulfur granules.
24
Q
What is the treatment for Actinomyces israelii?
A
Penicillin or amoxicillin for 6-12 months.
25
What is pharyngitis? How is it caused?
It is a sore throat. Acute pharyngitis most often caused by viruses however bacterial pharyngitis is MCC by S. pyogenes (Group A step).
26
Who most often gets pharyngitis (age range) and how is it spread?
5-15 year old and it is spread by respiratory droplets.
27
How does the infection cause phayngitis?
Bacteria attach to the mucosa (s. pyogenes) via M protein.
28
What are the symptoms associated with pharyngitis?
```
Sore throat
Fever
Chills
Abdominal Pain
Inflamed uvula/pharynx
Enlarged tonsils with grayish-white patchy exudate
```
29
What is NOT SEEN in pharyngitis?
Cough and congestion are ABSENT
30
How is s. pyogenes pharyngitis diagnosed?
Rapid strep test. Culture if the test is negative in children only.
31
What are the possible complication of S. pyogenes pharyngitis?
Glomerulonephritis
Scarlet Fever
Rheumatic Fever
32
What is the treatment for S. pyogenes pharyngitis?
Amoxicillin
33
What is epiglottitis and what is its progression?
It is the inflammation of the epiglottis which progresses rapidly. Can cause a potentially fatal obstruction of the airway.
34
What are the bacteria that most often cause epiglottitis?
HiB
H. parainfluenza
S. pneumonia
S. pyogenes (GAS)
Normal flora
35
What caused a reduction in epiglottitis cases?
Hib vaccine (reduced infection by H. influenza)
36
What are some associated SX with epiglottitis?
Severe sore throat
Fever
Dysphagia (difficulty swallowing)
Muffled voice
37
How do you diagnose epiglottitis?
Clinical SX and blood culture (often + for bacteria)
38
What is the treatment for epiglottitis?
First need to secure the airway (do not want obstruction) and then cefotaxime (3rd generation cephalosporins)
39
What is pneumonia?
It is the infection of the lung parenchyma (alvoli, alveolar duct, bronchioles)
40
What SX are associated with pneumonia?
```
Cough
Fever
Tachcardia
Dyspnea
Chest pain
Increased resp. rate
Use of accessory muscles
```
41
What are the different classification of pneumonia? (5)
1. Community-acquired (CAP) - outpatient or within 48 hours of hospital admission
2. Hospital-acuired (HAP) (in hospital for MORE than 48 hours)
3. Ventilator-associated (VAP)
4. Health-care associated (HCAP) - CAP with increased risk of multi-drug resistance (MDR) - nursing home, antibiotic use, prior hospitalization, dialysis, family member with MDR infection
5. Aspiration (AP)
42
What are the TYPICAL causes of CAP?
1. S. pneumonia
2. H. influenza (non-encapsulated)
3. S. aureus (after influenza infection - viral infect)
4. CA-MRSA
43
What SX are seen in CAP?
Fever
Dyspnea
Productive Cough
Chest Pain
44
What are the ATYPICAL bacterial pathogens that cause CAP? (All cannot be gram stained)
1. Legionella pneunophila (stains poorly)
2. Mycoplasma pneumonia (lacks cell wall)
3. Chlamydophilia pneumonia (lacks peptidoglycan)
45
What are the zoonotic atypical bacterial pathogens?
1. Chlamydophila psittaci (lacks peptidoglycan layer)
| 2. Francisella tularensis (stains poorly)
46
What SX are seen in CAP caused by atypical bacterial pathogens?
Cough which is NOT productive as well as extra pulmonary findings.
47
What does legionella pneumophila pneumonia cause?
Legionnaires disease
48
How is legionella pneumophila transmitted?
Inhalation of contaminated water vapours (questions are usually associated with recent hotel stays or cruises in which there is an air conditioner system)
49
What are the SX associated with legionella pneumophila?
```
Legionnaires Disease:
High fever
Chills
Slight productive cough (sputum may contain blood)
Diarrhea
Abdominal pain
Headache
Confusion
Changes in mental status
```
UNTREATED MORTALITY: 30%
50
How do you diagnose legionella pneumophila?
Culture of legionella in unrinary antigen test.
51
What is another disease caused by legionella pneumophila? What do you see? Treatment?
Pontiac fever
SX: Mild and self limiting, malaise, fatigue, fever, myalgias, headache.
Treatment: NONE
52
What is the physiology and structure of legionella pneumophila?
Gram negative rod (bacillus)
Obligate aerobe
Facultative intracellular pathogen
53
How is legionella pneumophila transmitted? Pathogenesis?
Is it transmitted by inhalation of contaminated water vapour. It enters the alveoli and it phagocytosed by macrophages where it can then multiply by inhibiting phagolysosome formation.
54
What diseases are caused by legionella pneumophila? (2)
Legionnaires disease
| Pontiac fever
55
How is legionella pneumophila treated?
Levofloxacin
56
How is mycoplasma pneumoniae transmitted? Who is it common among?
It is transmitted by respiratory droplets and requires close contact. It is common among college students and soldiers (epidemic outbreaks).
57
What are the virulence factors of mycoplasma penuomniae? (3)
It has adhesins that allow attachment to respiratory tract mucosa. It has the ability to kill ciliated epithelial cells. It is also resistant to cell wall active antibiotics (doesn't have a cell wall)
58
What SX are seen in bacterial infection with mycoplasma penuomniae?
```
Fever
Malaise
Headache
Sore throat
Nasal congestion
Non productive cough
```
59
What is the physiology and structure of mycoplasma penuomniae?
Lacks a cell wall, its cytoplasmic membrane contains sterols and it is an obligate aerobe.
60
How is mycoplasma penuomniae spread? Who is commonly infected?
Spread by resp droplets and outbreaks seen in college students and soldiers.
61
What diseases are caused by mycoplasma penuomniae? (2)
Mild upper respiratory tract infections
| Pneumonia (less common)
62
How do you DX mycoplasma penuomniae?
Slow growth in plates, use serology.
63
What is the TX for mycoplasma penuomniae?
Doxycycline
64
What is the physiology and structure of chlamydophila pneumonia?
It is an obligate intracellular pathogen with inner and outer membranes that lacks a peptidoglycan layer. Elementary bodies and reticulate bodies can be seen.
NOTE: Elementary body - an infectious particle of any of several microorganisms; especially : a chlamydial cell of an extracellular infectious form that attaches to receptors on the membrane of the host cell and is taken up by endocytosis
Reticulate body - a chlamydial cell of a spherical intracellular form that is larger than an elementary body and reproduces by binary fission
65
What does chlamydophila psittaci cause? What are the SX seen?
Psittacosis (zoonotic transmission from birds) in which it produces a non-productive cough, chest pain, high fever and muscle aches. CAN PRODUCE A SEVERE PNEUMONIA.
66
Chlamydophila pneumonia causes what? How is it spread?
It is a common cause of atypical pneumonia.
| It spreads by respiratory droplets.
67
What diseases are caused by chlamydophila pneumonia?
Respiratory tract infections ranging from asymptomatic to severe pneumonia.
68
How is chlamydophila pneumonia diagnosed?
Serology
69
What is the treatment for chlamydophila pneumonia?
Doxycyline
70
How does francisella tularensis cause pneumonia?
Pulmonary Tularemia: Ticks and wild animals carry the disease and can be spread inhalation of aerosol from infected animal or hematogenous spread from ulceroglandular tularemia causing atypical pneumonia.
71
What are the SX of pulmonary tularemia?
A non productive cough, dyspnea and chest pain.
72
What is the diagnosis for CAP?
Gram stain and culture sputum
Legionella urinary antigen test
PCR
73
What is the TX for CAP?
Empiric antibiotic TX until organism and sensitivity are known.
NOTE: Empiric antibiotics depend on patients history of previous antibiotic use, underlying diseases and if the patient will be admitted to the hospital or not.
74
What is hospital acquired pneumonia? (HAP)
It is pneumonia that develops in a patient who has been in the hospital for more than 48 hours.
75
What is special about HAP? How do you TX HAP?
Pathogens more likely to be multi drug resistant and the patients are likely to be unable to cough enough to provide a sputum sample for culture.
TX: Empiric therapy based on multi drug resistance
76
What is ventilator associated pneumonia?
Pneumonia that develops in a patient who has been intubated for more than 48 hours. Risk increases with length of intubation.
77
What are the SX/signs seen in VAP?
Fever
Purulent secretions
Leukocytosis (increased WBC)
78
Which bacteria are more often seen in VAP?
Pseudomonas aeruginosa
MRSA
*these pathogens are more likely to be multi drug resistant and result in a HIGHER MORTALITY when compared to HAP
79
What is the treatment for VAP?
TX: Empiric therapy based on multi drug resistance
80
What is health care associated pneumonia?
This is pneumonia in a patient with some association to the health care system (i.e., nursing home, antibiotic use, prior hospitalization, dialysis, family member with MDR infection)
81
What bacteria are likely to cause HCAP?
CAP organisms are more likely to cause HCAP. Pathogens are more likely to be MDR when compared to CAP.
82
What is the TX for HCAP?
Empiric therapy depends on MDR pattern in hospital or ICU.
83
What is aspiration pneumonia (AP)?
It is pneumonia caused by aspiration of bacteria from oral or pharyngeal areas.
84
What are some predisposing conditions that cause AP?
Conditions that alter consciousness and reduce the gag reflex such as drugs, alcohol, stroke and anesthesia.
85
What are the SX of CAP?
Cough with PURULENT SPUTUM, fever, chills, malaise, myalgias, dyspnea and chest pain - similar to CAP.
86
Which bacteria most commonly infect AP?
Oral anaerobes (polymicrobial infections) common.
1. Bacteroides
2. Peptostreptococcus
3. Porphyromonas
4. Prevotella
87
What is the treatment for AP?
Need to tx by including coverage for anaerobes and MRSA in empiric antibiotics.
88
What is the cause of lung abscesses? What are some predisposing conditions?
It is caused by aspiration of bacteria from oral of pharyngeal areas. Conditions that alter consciousness and reduce the gag reflex such as drugs, alcohol, stroke and anesthesia. (SAME AS ASPIRATION PNEUMONIA)
89
What are symptoms associated with lung abscesses?
Night sweats, fatigure and anemia are common.
90
Which bacteria are associated with lung abscesses?
Oral anaerobes (polymicrobial infection) and streptococci
1. Bacteroides
2. Peptostreptococcus
3. Porphyromonas
4. Prevotella
AGAIN SAME AS AP
91
How to TX lung abscesses?
Clindamycin
92
How is tuberculosis caused?
It is caused by mycobacterium tuberculosis.
93
What is the physiology and structure of mycobacterium tuberculosis?
It has a gram + cell wall structure (CANNOT STAIN DUE TO MYCOLIC ACIDS). It is a facultative intracellular pathogen.
94
How do you stain mycobacterium tuberculosis?
Acid fast stain (Ziehl Neelson)
95
What disease is caused by mycobacterium tuberculosis?
Tuberculosis
96
How do you diagnose and treat tuberculosis? Latent? Active? MDR-TB? XDR-TB?
Latent TB: PPD or IGRA test - TX - 9 months of isoniazid to prevent reactivation
Active: Acid fast stain, culture (2-3 weeks) or PCR
CXR - for latent TB (may see granulomas)
Usual TX is with isoniazid, rifampin, pyrazinamide, ethanbutol (6-9 months)
MDR-TB: treatment for multi drug resistant TB that is resistant to at least isoniazid and rifampon, use 3-5 new drugs (20 months of TX)
XDR-TB: resistance to isoniazid, rifampin and two other classes of drugs used to treat MDR-TB, 5-9 drugs used to TX and HIGH MORTALITY
97
How is mycobacterium tuberculosis transmitted? Where does it grow?
Respiratory droplets from an infected person (person-person transmission). The bacteria is engulfed by alveolar macrophages and reproduces within the macrophages.
98
What happens if exposed to mycobacterium tuberculosis?
1. The bacteria can be destroyed.
2. Active TB - bacteria spreads throughout the lung and rest of body by blood causing productive cough, fever, weight loss, night sweats, chest pain and fatigue
3. Latent TB - bacteria is walled off in a granuloma, may or may not be visible on chest X-ray (CXR)
99
What are the SX associated with an active TB infection?
Productive cough, fever, weight loss, night sweats, chest pain and fatigue
100
What are the most common extrapulmonary sites of TB infection (most common to least common)
1. Lymph nodes
2. Pleura
3. Genitourinary tract
4. Bones and joints
5. Meninges
6. Peritoneum
7. Pericardium
101
How is inhalation anthrax caused? Pathogenesis of inhalation anthrax?
It is caused by Bacillus anthracis spores that can be inhaled. The spores are engulfed by alveolar macrophages and then travel to the lymph nodes. The spores germinate and the vegetative cell can replicate leading to bacteria.
102
What is the structure and physiology of Bacillus anthracis?
Gram positive rod (bacillus)
103
What are the SX of inhalation anthrax?
Fever, chills, dyspnea, cough, headache, vomiting, chest and abdominal pain which PROGRESSES to HIGH FEVER, EDEMA, ENLARGED MEDIASTINAL LYMPH NODES (between sternum and spinal column) and MENINGITIS
NOTE: Untreated mortality rate 95% within 3 days
104
What is the cause of diphtheria?
It is caused by inhalation of cornybacterium diphtheria
105
What is the structure and physiology of cornybacterium diphtheria? Which strain causes disease?
Gram positive rod (bacillus). Disease caused ONLY by strains carrying the TOX genes by a lysogenic phage.
106
What is the pathogenesis of cornybacterium diphtheria?
A-B toxin preferentially binds to HEART and NERVE cells. Toxin can cause severe cardiac and neurological complications. Bacteria multiply at site on pharynx and the toxin causes local damage causing a pseudomembrane.
107
Where do cornybacterium diphtheria replicate?
In the pharynx causing sudden sore throat, malaise, low grade fever, exudate that forms a pseudomembrane (which is adherent and covers the tonsils, uvula, palate - can extend to the nasopharynx or down into the larynx)
108
What is the danger of a pseudomembrane in the throat?
Is can obstruct the airway and cause death.
109
What is the treatment for cornybacterium diphtheria? Prevention?
TX: antitoxin and penicillin or erythromycin
Prevent: TDaP or DTaP vaccine - use a toxoid vaccine
110
What causes pertussis (whooping cough)? Mild form caused by?
It is caused by inhalation of bordetella pertussis. (A mild form is caused by bordetella parapertussis).
111
Is bordetella pertussis contagious?
HIGHLY
112
Most cases of pertussis are seen in? Deaths are most common in which age froup?
Children under 1 year old (the disease is much more serious in this group) and all fatalities seen are in children under the age of 6 months old (less than 3 doses of vaccine at this time)
113
The acceular pertussis vaccine should be given when? Frequency? How long does immunity last?
5 doses before age 6
1 dose as a teenage
1 dose as an adult
Immunity lasts only 3-5 years.
114
What are the virulence factors for pertussis? (3)
1. Adhesins to attach to ciliated respiratory epithelium
2. Tracheal cytotoxin: Inhibits cilia and thus prevents clearance of the organism
3. Pertussis toxin: AB5 which increases adenylate cyclase and increases production of respiratory secretions and mucus
115
What are the 3 stages of whooping cough (pertussis)? Length of each stage? SX of each stage?
1. Catarrhal stage - runny nose, sneezing, low grade fever (1-2 weeks)
2. Paroxysmal stage - whooping cough (series of coughs followed by an inspiratory whoop), vomiting, exhaustion common after coughing fit (2-4 weeks)
3. Convalescent stage - chronic stage (several weeks)
116
What are some complications of pertussis?
Pneumonia
| Encephalopathy
117
How is pertussis diagnosed?
Culture or PCR
118
What is the TX for pertussis?
Antibiotics for patients and household members. (REMEMBER: IT IS HIGHLY CONTAGIOUS)
119
What is the physiology and structure of bordetella pertussis? Transmission?
Gram negative bacillus and it is an obligate aerobe. Transmitted by respiratory droplets. HIGHLY CONTAGIOUS!!!
120
Which respiratory diseases are aggravated by bacteria? (2)
Cystic Fibrosis
| COPD
121
How are cystic fibrosis patients affected by bacteria? Why are infections difficult to treat (2 reasons)? Which bacteria? (2)
CF patients have repeated bacterial infections which is a major cause of death. MC - pseudomonas aeruginosa, burkolderia capacia (GN rod). Infections are difficult to treat due to antibiotic resistance and biofilm formation.
122
How are COPD patients affects by bacteria? Which bacteria? (4)
They have exacerbations due to bacterial infections (very common). Commonly infected by H. influenza (non typable), moraxella catarrhalis, pseudomonas aeruginosa, s. pneumoniae
